We have been converted without choice to a Microsoft Exchange 
proprietary email server, although IMAP service has been retained. I 
have 64 bit X86-64 Thunderbird on my office machine, and 32 bit IA-32 
Thunderbird on my laptop, both under SL6x (64 bit office, 32 bit 
laptop).  The office machine is 4 core, my laptop is 2 core.  On my 
office machine, when using the MS IMAP server, Thunderbird runs very, 
very slowly, with a single core reported load over 100 percent -- and 
does not appear to be using more than one core.  On my laptop, 
Thunderbird has acceptable performance, and typically shows a load of 10 
percent.  Office LAN is IEEE 802.3 at 100 Mbit/sec; home is over IEEE 
802.11 through a DSL box from the telephone common carrier.

Anyone else having a similar experience?  Is 64 bit Tbird significantly 
different from 32 bit Tbird?

Yasha Karant